CN110953889B - Large Bi-2212 superconducting coil heat treatment furnace system and pressure control method thereof - Google Patents
Large Bi-2212 superconducting coil heat treatment furnace system and pressure control method thereof Download PDFInfo
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F27—FURNACES; KILNS; OVENS; RETORTS
- F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
- F27D7/00—Forming, maintaining, or circulating atmospheres in heating chambers
- F27D7/06—Forming or maintaining special atmospheres or vacuum within heating chambers
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F27—FURNACES; KILNS; OVENS; RETORTS
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- F27D19/00—Arrangements of controlling devices
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- H—ELECTRICITY
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- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B12/00—Superconductive or hyperconductive conductors, cables, or transmission lines
- H01B12/02—Superconductive or hyperconductive conductors, cables, or transmission lines characterised by their form
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
- H01F41/02—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets
- H01F41/04—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets for manufacturing coils
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F6/00—Superconducting magnets; Superconducting coils
- H01F6/06—Coils, e.g. winding, insulating, terminating or casing arrangements therefor
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F27—FURNACES; KILNS; OVENS; RETORTS
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- F27D7/00—Forming, maintaining, or circulating atmospheres in heating chambers
- F27D7/06—Forming or maintaining special atmospheres or vacuum within heating chambers
- F27D2007/063—Special atmospheres, e.g. high pressure atmospheres
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F27—FURNACES; KILNS; OVENS; RETORTS
- F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
- F27D19/00—Arrangements of controlling devices
- F27D2019/0006—Monitoring the characteristics (composition, quantities, temperature, pressure) of at least one of the gases of the kiln atmosphere and using it as a controlling value
- F27D2019/0009—Monitoring the pressure in an enclosure or kiln zone
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F27—FURNACES; KILNS; OVENS; RETORTS
- F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
- F27D19/00—Arrangements of controlling devices
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- F27D2019/0068—Regulation involving a measured inflow of a particular gas in the enclosure
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- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
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- Y02E40/60—Superconducting electric elements or equipment; Power systems integrating superconducting elements or equipment
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Abstract
The invention discloses a large Bi-2212 superconducting coil heat treatment furnace system and a pressure control method thereof. The system design requirements of the Bi-2212 superconducting coil for heat treatment of high temperature and high pressure are met. The design of the temperature-equalizing radiation screen in the heat treatment furnace improves the uniformity of the heat treatment temperature of the superconducting coil on one hand and ensures the cleanliness of the superconducting coil on the other hand. The pressure control method comprises the following stages: gas replacement in the pressure-resistant furnace shell; gas replacement in the uniform-temperature radiation screen; and synchronously pressurizing and micro-feeding and micro-discharging gas. The invention has the advantages that the system adopts an intrinsic safety design, and has high safety reliability and high cost performance. The system is suitable for processing large Bi-2212 superconducting coils with the outer diameter of 0.1-3m and the height of 0.1-3 m. The heat treatment temperature of the superconducting coil can be effectively controlled, the temperature uniformity of the superconducting coil can reach +/-5 ℃, and the superconducting performance of the Bi-2212 superconducting coil is improved.
Description
Technical Field
The invention relates to the technical field of heat treatment of large Bi-2212 superconducting coils, in particular to a large Bi-2212 superconducting coil heat treatment furnace system and a pressure control method thereof.
Background
With the development of technology and research, the requirement on the magnetic field intensity is also increased, and ultrahigh background magnetic fields are required to be provided for large-scale accelerator magnets, fusion device magnets and the like. Low temperature superconductor Nb3Sn and NbTi, etc. are supported thereonCritical field (Hc)2) Has become increasingly unable to meet the demand. Therefore, the high-temperature superconducting material with high critical field can meet the development requirement of the high-field magnet in the future.
The critical temperature of the Bi-2212 high-temperature superconducting material is 85K, the 4.2K upper critical magnetic field is 100T, the magnetic field current-carrying performance is excellent, and the magnetic material is one of the preferred materials of large-scale super-strong magnetic field magnets. Bi-2212 is the only material which can be prepared into an isotropic round wire in the current high-temperature superconducting materials, and can be twisted into a large-current armored pipe cable conductor (CICC).
After the Bi-2212 superconducting coil is wound and formed, a Bi-2212 superconducting phase is generated by certain heat treatment. The heat treatment is a key technology for manufacturing the Bi-2212 superconducting coil, and the quality of the heat treatment directly determines the superconducting performance of the future coil. The heat treatment of the Bi-2212 superconducting coil needs to solve the following two key technical problems.
1. Heat treatment temperature and temperature uniformity. The heat treatment system of Bi-2212 is as follows: raising the temperature from room temperature to 830 ℃ at 160 ℃/h, keeping the temperature for 2h at 830 ℃, raising the temperature from 830 ℃ to 888 ℃ at 50 ℃/h, keeping the temperature for 0.5h at 888 ℃, reducing the temperature from 888 ℃ to 878 ℃ at 10 ℃/h, reducing the temperature from 878 ℃ to 840 ℃ at 2.5 ℃/h, keeping the temperature at 840 ℃ for 48h, and then reducing the temperature to room temperature at a cooling rate of 80 ℃/h. The temperature uniformity of the Bi-2212 superconducting coil in the heat treatment process is within +/-5 ℃.
2. Solves the high pressure problem of oxygen-argon mixed gas in the heat treatment furnace. Oxygen-argon mixed gas needs to be continuously introduced in the heat treatment process of the Bi-2212 superconducting coil, the proportion of oxygen is between 2 and 3.4 percent, and the pressure in the furnace is maintained between 3 and 5 Mpa.
At present, no large heat treatment furnace for heat treatment of Bi-2212 materials exists at home, and the difficulty of overcoming mainly comprises the following aspects:
(1) the heat treatment furnace needs to bear high-temperature, high-pressure and oxygen-enriched environment;
(2) the construction and material selection and processing of the heat treatment furnace need to fully consider the safety and reliability factors;
(3) there are complications in equipment and process control during heat treatment.
Disclosure of Invention
In order to solve the problems, the invention designs a large-scale heat treatment system for the Bi-2212 coil for the first time by adopting an internal heating type heat treatment furnace idea and simultaneously utilizes the pressure balance principle to ensure that the inside of a heating chamber is not subjected to pressure, thereby ensuring the safety of the system and the effectiveness of a material heat treatment process. The heat treatment system of the invention is an internal heating type heating furnace, and meets the technical requirements of Bi-2212 coil heat treatment on high temperature and high pressure. The design of the temperature-equalizing radiation screen in the heat treatment furnace improves the uniformity of the heat treatment temperature of the superconducting coil on one hand, and ensures the cleanliness of the superconducting coil on the other hand, and the method is an atmosphere supply and pressure control method with high precision, high effectiveness and high reliability.
The invention provides a large Bi-2212 superconducting coil heat treatment furnace system, which comprises:
the device comprises a furnace pressing shell, a pressure-resistant furnace cover, a heat insulation layer, a heating chamber, a temperature-equalizing radiation screen, a pressure-equalizing pipeline, a supporting workbench, a liquid argon tank, an oxygen-argon mixed gas tank, a gas pipeline and a safety device;
a gas pipeline reserved port, a cooling device and a thermocouple reserved port are arranged on the pressure-resistant furnace shell, a hanging ring is arranged above the pressure-resistant furnace cover, and a plurality of groups of reinforcing ribs are arranged below the pressure-resistant furnace cover and connected with the upper heat-insulating layer;
the heat insulation layer is of a sandwich structure and consists of a stainless steel outer screen, a molybdenum inner screen and heat insulation fibers sandwiched between the stainless steel outer screen and the molybdenum inner screen, the heat insulation layer is positioned in the pressure-resistant furnace shell, and the thickness of the heat insulation layer is between 100 and 250 mm;
the heating chamber comprises a heating belt fixed on an inner screen of the heat insulation layer, and the uniform-temperature radiation screen is positioned in the heating chamber and made of high-temperature alloy steel; the uniform temperature radiation screen is positioned above the supporting workbench, an inlet and an outlet of a gas pipeline are reserved on the uniform temperature radiation screen, the Bi-2212 superconducting coil is positioned in the uniform temperature radiation screen, the uniform pressure pipeline is positioned in the heat insulation layer, the heating chamber is communicated with a pressure-resistant furnace shell outside the heat insulation layer, the air pressure inside and outside the heat insulation layer is kept consistent, the supporting workbench is fixed at the bottom of the pressure-resistant furnace shell, penetrates through the heat insulation layer and is a heating workbench for placing the superconducting coil, the oxygen-argon mixed gas tank is used for providing the pressure of 3-5Mpa, and a first stop valve, a first pressure reducer and a first flowmeter are sequentially arranged behind the oxygen-argon mixed gas tank and are in threaded connection with the gas pipeline; the liquid argon tank provides 3-6Mpa of pressure, is equipped with second stop valve, second pressure reducer, second flowmeter, third stop valve behind it in proper order, carries out threaded connection with the gas line, the gas line all have cooling device with withstand voltage stove outer covering continuous part, the gas line divide into samming radiation screen air inlet pipeline, samming radiation screen gas outlet pipeline, withstand voltage stove outer covering air inlet pipeline and withstand voltage stove outer covering gas outlet pipeline, the gas line is connected with safety device, safety device includes first relief valve, second relief valve, rupture disc, first manometer, second manometer and controlling means.
Furthermore, the pressure-resistant furnace shell is a cylindrical stainless steel tank body, the thickness of the tank body is 5-30mm, the diameter of the disc base is 4-8m, the height of the disc base is 4-9m, and the pressure-resistant furnace shell and the reserved pipeline are sealed in a welding mode.
Furthermore, the pressure-resistant furnace cover is designed to be arched, is made of stainless steel materials and has a thickness of 10-30mm, is positioned above the pressure-resistant furnace shell and is connected in a sealing mode in a welding mode.
Furthermore, the total power of the heating chamber is 100-300KW, the heating belt is made of molybdenum material, the distance between the heating belt and the inner screen of the heat insulation layer is 50-150mm, and each heating zone is provided with a standby heating belt.
Furthermore, the temperature-equalizing radiation screen is designed according to the size of the Bi-2212 superconducting coil, the distance between the temperature-equalizing radiation screen and the heating belt is 50-200mm, and the temperature-equalizing radiation screen can bear the pressure of 1 MPa.
Furthermore, the diameter of the hole of the pressure equalizing pipeline is 1500mm, the wall thickness is 5-20mm, and the gas inlet and outlet pipelines are respectively positioned in the pressure equalizing pipeline.
Furthermore, the diameter of the hole of the gas pipeline is 20-100mm, the wall thickness is 2-10mm, the gas outlet pipeline of the uniform temperature radiation screen is provided with a third pressure reducer and a first oxygen content analyzer, and the gas outlet pipeline of the pressure-proof furnace shell is provided with a fourth pressure reducer and a second oxygen content analyzer.
Furthermore, the uniform temperature radiation screen gas outlet pipeline is connected with the pressure-proof furnace shell gas outlet pipeline, the uniform temperature radiation screen gas outlet pipeline is provided with a first safety valve, the pressure-proof furnace shell gas outlet pipeline is provided with a second safety valve, and the pipeline provided with the rupture disk is bridged between the two gas outlet pipelines;
furthermore, the rated working pressure of the safety valve is 5.5MPa, and the rated working pressure difference of the rupture disk is 1 MPa.
According to another aspect of the invention, the invention also provides a pressure control method of the large Bi-2212 superconducting coil heat treatment furnace system, which comprises the following steps:
the method comprises the following steps that firstly, gas in the pressure-resistant furnace shell is replaced, a second stop valve of an argon gas inlet pipeline is opened, a second pressure reducer is opened, air in the pressure-resistant furnace shell is emptied, the pressure in the pressure-resistant furnace shell is monitored, and a fourth pressure reducer of an air outlet pipeline is adjusted to maintain the pressure in the pressure-resistant furnace shell within 1 Mpa;
step two, gas replacement in the uniform temperature radiation screen, namely opening a first stop valve of an oxygen-argon mixed gas inlet pipeline, opening a first pressure reducer, emptying air in the uniform temperature radiation screen, monitoring the pressure in the uniform temperature radiation screen, adjusting a third pressure reducer of an outlet pipeline, synchronously performing gas replacement in the pressure-resistant furnace shell and gas replacement in the uniform temperature radiation screen, and respectively adjusting the inlet flow of the oxygen-argon mixed gas pipeline and the inlet flow of the argon pipeline so as to keep the pressure in the uniform temperature radiation screen and the pressure in the pressure-resistant furnace shell synchronous;
monitoring the oxygen content of gas in the pressure-resistant furnace shell by using a second oxygen analyzer, monitoring the oxygen content of gas in the temperature-uniform radiation-resistant screen by using a first oxygen analyzer when the oxygen content of the gas in the pressure-resistant furnace shell is lower than 10ppm, and stopping gas replacement when the oxygen content of the gas in the temperature-uniform radiation screen is consistent with the oxygen content of the oxygen-argon mixed gas;
step four, synchronously pressurizing the furnace, and adjusting a fourth pressure reducer of the pressure-proof furnace shell exhaust pipeline and a third pressure reducer of the temperature-equalizing radiation screen exhaust pipeline to ensure that the pressure in the temperature-equalizing radiation screen and the pressure in the pressure-proof furnace shell are synchronously increased, and finishing pressurization when the two pressures reach 5Mpa simultaneously;
and step five, performing micro-feeding and micro-discharging of gas, adjusting the gas inlet flow of the uniform temperature radiation screen and the pressure-proof furnace shell gas inlet pipeline, performing micro-feeding and micro-discharging of the gas in the uniform temperature radiation screen and the pressure-proof furnace shell, keeping the pressure synchronous, and then heating.
The invention has the advantages that:
(1) the design of an internal heating type heat treatment furnace is adopted, a pressure-resistant furnace shell is used as a pressure-bearing part, a pressure balance method is adopted to ensure that the inner part of the furnace does not bear pressure, a temperature-equalizing radiation screen is adopted to control oxygen in the radiation screen, and the pressure-resistant furnace shell is ensured not to be oxidized;
(2) the internal heating heat treatment furnace ensures that the temperature of the pressure-resistant furnace shell is not too high due to the action of the heat insulation layer, so that most of steel can bear the pressure of 5MPa, the quality detection and detection of each step can be completed while the processing precision is ensured in the processing process, and the problem of too large equipment processing is solved;
(3) the heat treatment furnace is uniformly designed and manufactured in a safe mode, and safety evaluation is carried out after equipment manufacturing is finished.
The system is reliable, has high cost performance, is suitable for processing large Bi-2212 superconducting coils with the outer diameter of 0.1-3m and the height of 0.1-3m, can effectively control the heat treatment temperature of the superconducting coils, can ensure the surface cleanliness of the superconducting coils to be +/-5 ℃, and can improve the superconducting performance of the magnet coils. The system adopts an explosion-proof safety design, reliably reduces the analysis of the Bi-2212 superconducting coil on high-temperature and high-pressure heat treatment, and ensures the safety of devices and personnel.
Drawings
FIG. 1 is a schematic view of a heat treatment furnace system according to the present invention.
Description of reference numerals:
1 oxygen argon mixed gas tank, 2 first stop valve, 3 first pressure reducer, 4 first flow meter, 5 welding mode, 6 lifting ring, 7 pressure-proof furnace cover, 8 groups of reinforcing ribs, 9 heat-insulating layer, 10 stainless steel outer screen, 11 heat-insulating fiber, 12 molybdenum inner screen, 13 heating band, 14 uniform temperature radiation screen, 15Bi-2212 superconducting coil, 16 uniform temperature radiation screen gas inlet pipeline, 17 uniform temperature radiation screen gas outlet pipeline, 18 supporting workbench, 19 pressure-proof furnace shell, 20 uniform pressure pipeline, 21 liquid argon tank, 22 second stop valve, 23 second pressure reducer, 24 second flow meter, 25 third stop valve, 26 first pressure meter, 27 third pressure reducer, 28 first safety valve, 29 thermocouple port, 30 cooling device, 31 second pressure meter, 32 fourth pressure reducer, 33 second safety valve, 34 rupture disk, 35 first oxygen content analyzer, 36 second oxygen content analyzer, 37 heating chamber, 34 heating chamber, 30 cooling chamber, 31 second pressure meter, 32 fourth pressure reducer, 33 second safety valve, 34 rupture disk, 35 first oxygen content analyzer, 36 second oxygen content analyzer, 5 heating chamber, 6 lifting ring, 7 pressure-proof furnace cover, 8 groups of heat-proof furnace, 9 groups of heat-proof furnace groups, 9 groups of heat-type, 9 groups of heat-type, 9 groups of heat-type, 9 groups, groups of heat-type, 9 groups of heat-type, groups of heat-type groups, 38 pressure-proof furnace shell inlet pipeline and 39 pressure-proof furnace shell outlet pipeline.
Detailed Description
The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments, and all other embodiments obtained by a person skilled in the art based on the embodiments of the present invention belong to the protection scope of the present invention without creative efforts.
As shown in fig. 1, the large Bi-2212 superconducting coil heat treatment furnace system comprises a pressure-resistant furnace shell 19, a pressure-resistant furnace cover 7, a heat-insulating layer 9, a heating chamber 37, a uniform temperature radiation screen 14, a pressure equalizing pipeline 20, a supporting workbench 18, a liquid argon tank 21, an oxygen-argon mixed gas tank 1, a uniform temperature radiation screen air inlet pipeline 16, a uniform temperature radiation screen air outlet pipeline 17, a pressure-resistant furnace shell air inlet pipeline 38, a pressure-resistant furnace shell air outlet pipeline 39, a first safety valve 28, a second safety valve 33 and a rupture disk 34. The pressure-resistant furnace shell 19 is provided with a gas pipeline reserved port, a cooling device 30 and a thermocouple reserved port 29, a hanging ring 6 is arranged above the pressure-resistant furnace shell 7, a plurality of groups of reinforcing ribs 8 are arranged below the pressure-resistant furnace shell 7 and are connected with an upper heat-insulating layer 9, the heat-insulating layer 9 is of a sandwich structure and consists of a stainless steel outer screen 10, a molybdenum inner screen 12 and a heat-insulating fiber 11 clamped in the middle, the heat-insulating layer 9 is positioned in the pressure-resistant furnace shell 19, the thickness of the heat-insulating layer 9 is 100-250mm, the heating chamber 37 comprises a heating belt 13 fixed on the heat-insulating layer inner screen 12, the uniform-temperature radiation screen 14 is positioned in the heating chamber 37 and is made of high-temperature alloy steel, the uniform-temperature radiation screen 14 is positioned above the supporting workbench 18, a gas pipeline inlet and an outlet are reserved on the uniform-temperature radiation screen 14, the Bi-2212 superconducting coil 15 is positioned in the uniform-temperature radiation screen 14, the uniform-temperature pipeline 20 is made of high-temperature alloy steel, the oxygen-argon mixed gas tank 1 can provide 3-5Mpa pressure, and is sequentially provided with a first stop valve 2, a first pressure reducer 3 and a first flow meter 4 which are in threaded connection with a uniform temperature radiation screen inlet pipeline 16, the uniform temperature radiation screen inlet pipeline 16, a uniform temperature radiation screen outlet pipeline 17, a uniform pressure furnace shell inlet pipeline 38 and a uniform pressure furnace shell outlet pipeline 39 which are connected with the pressure furnace shell 19 are all provided with a cooling device at the connecting part of the uniform temperature radiation screen inlet pipeline 16, the uniform temperature radiation screen outlet pipeline 17, the pressure furnace shell inlet pipeline 38 and the pressure furnace shell outlet pipeline 39 which are connected with the pressure furnace shell 19 30, the safety device comprises a first safety valve 28, a second safety valve 33, a rupture disc 34, a first pressure gauge 26, a second pressure gauge 31 and a control device.
The pressure-resistant furnace shell 19 is a cylindrical stainless steel tank body, the thickness of the tank body is 5-30mm, the diameter of the disc base can reach 4-8m, the height of the disc base can reach 4-9m, and the pressure-resistant furnace shell 19 and a reserved pipeline are sealed in a welding mode.
The pressure-resistant furnace cover 7 is designed in an arch shape, the pressure-resistant furnace cover 7 is made of stainless steel materials, the thickness of the pressure-resistant furnace cover 7 is 10-30mm, and the pressure-resistant furnace cover 7 is positioned above the pressure-resistant furnace shell 19 and is in sealing connection in a welding mode 5.
The heating chamber 37 is divided into three heating zones and realizes the independent control of heating power, the total power is 100-300KW, the heating belt 13 is made of molybdenum material, the distance between the heating belt 13 and the inner screen 12 of the heat insulation layer is 50-150mm, and each heating zone is provided with a plurality of standby heating belts.
The temperature-equalizing radiation screen 14 is designed according to the size of the Bi-2212 superconducting coil 15, the distance between the temperature-equalizing radiation screen 14 and the heating belt 13 is 50-200mm, and the temperature-equalizing radiation screen 14 mainly bears high temperature and can bear the pressure of 1 MPa.
The hole diameter of the pressure equalizing pipeline 20 is 100-1500mm, the wall thickness is 5-20mm, and the gas inlet and outlet pipelines 16 and 17 are respectively positioned in the pressure equalizing pipeline.
The diameter of the hole of the gas pipeline is 20-100mm, the wall thickness is 2-10mm, and the tail end of the gas pipeline is provided with a first oxygen content analyzer 35 and a second oxygen content analyzer 36.
In the safety device, a temperature-equalizing radiation screen outlet pipeline 17 is connected with a pressure-resistant furnace shell outlet pipeline 39, on one hand, two outlet pipelines are provided with a first safety valve 28 and a second safety valve 33, and on the other hand, a pipeline provided with a rupture disk 34 is bridged between the two outlet pipelines. In the process of synchronously pressurizing the uniform temperature radiation screen 14 and the pressure-resistant furnace shell 19, if the pressure of the uniform temperature radiation screen 14 exceeds 5.5MPa, the first safety valve 28 is started to start pressure relief; if the pressure of the pressure-resistant furnace shell 19 exceeds 5.5MPa, the second safety valve 33 is started to start pressure relief; when the pressure distribution of the uniform temperature radiation flat screen 14 and the pressure-proof furnace shell 19 is uneven, if the pressure difference between the uniform temperature radiation flat screen 14 and the pressure-proof furnace shell 19 exceeds 1MPa, the rupture disk 34 starts to explode, so that the pressure of the uniform temperature radiation flat screen 14 and the pressure of the pressure-proof furnace shell 19 are kept balanced.
In the safety device, the rated working pressure of the first safety valve 28 and the second safety valve 33 is 5.5MPa, and the rated working pressure difference of the rupture disk 34 is 1 MPa.
According to an embodiment of the invention, the invention also provides a pressure control method of the large Bi-2212 superconducting coil heat treatment furnace system, which comprises the following specific steps:
a, gas replacement in a pressure-resistant furnace shell is carried out, a second stop valve of an argon gas inlet pipeline is opened, a second pressure reducer is opened, air in the pressure-resistant furnace shell is emptied, the pressure in the pressure-resistant furnace shell is monitored, and a fourth pressure reducer of an air outlet pipeline is adjusted, so that the pressure in the pressure-resistant furnace shell is maintained within 1 Mpa;
b, gas replacement in the uniform temperature radiation screen, namely opening a first stop valve of an oxygen-argon mixed gas inlet pipeline, opening a first pressure reducer, emptying air in the uniform temperature radiation screen, monitoring the pressure in the uniform temperature radiation screen, adjusting a third pressure reducer of an outlet pipeline, synchronously performing gas replacement in the pressure-resistant furnace shell and gas replacement in the uniform temperature radiation screen, and respectively adjusting the inlet flow of the oxygen-argon mixed gas pipeline and the inlet flow of the argon gas pipeline so that the pressure in the uniform temperature radiation screen and the pressure in the pressure-resistant furnace shell are kept synchronous;
monitoring the oxygen content of gas in the pressure-resistant furnace shell by using a second oxygen analyzer, monitoring the oxygen content of gas in the temperature-uniform radiation-resistant screen by using a first oxygen analyzer when the oxygen content of the gas in the pressure-resistant furnace shell is lower than 10ppm, and stopping gas replacement when the oxygen content of the gas in the temperature-uniform radiation screen is consistent with the oxygen content of the oxygen-argon mixed gas;
d, synchronously pressurizing the furnace, and adjusting a fourth pressure reducer of the pressure-proof furnace shell exhaust pipeline and a third pressure reducer of the temperature-equalizing radiation screen exhaust pipeline to ensure that the pressure in the temperature-equalizing radiation screen and the pressure in the pressure-proof furnace shell are synchronously increased, and finishing pressurization when the two pressures reach 5Mpa simultaneously;
and E, performing micro-feeding and micro-discharging on the gas, adjusting the gas inflow rate of the gas inlet pipeline of the uniform temperature radiation screen and the pressure-resistant furnace shell, performing micro-feeding and micro-discharging on the gas in the uniform temperature radiation screen and the pressure-resistant furnace shell, keeping the pressure synchronous, and then heating.
In the actual high-temperature high-pressure heat treatment process, a safety problem is a considerable problem. Therefore, the system of the present invention makes consideration of the safety of the heat treatment at the beginning of the design. The working principle of the safety device is as follows: when the pressure in the uniform temperature radiation screen or the pressure in the pressure-proof furnace shell exceeds 5.5MPa, the safety valve starts to release pressure, and when the pressure difference between the gas in the uniform temperature radiation screen and the gas in the pressure-proof furnace shell exceeds 1MPa, the rupture disk starts to explode, so that the pressure of the rupture disk and the pressure of the gas in the uniform temperature radiation screen are uniform, and the safety of the device and personnel is ensured.
The invention has the advantages of safe and reliable system and high cost performance. The method is suitable for processing the large Bi-2212 superconducting coil with the outer diameter of 0.1-3m and the height of 0.1-3m, can effectively control the heat treatment temperature of the superconducting coil, ensures the temperature uniformity of the superconducting coil to be +/-5 ℃, simultaneously ensures the surface cleanliness of the superconducting coil, and improves the superconducting performance of the magnet coil. The system adopts an intrinsic safety design, reliably reduces the analysis of the Bi-2212 superconducting coil on high-temperature and high-pressure heat treatment, and ensures the safety of devices and personnel.
Although illustrative embodiments of the present invention have been described above to facilitate the understanding of the present invention by those skilled in the art, it should be understood that the present invention is not limited to the scope of the embodiments, but various changes may be apparent to those skilled in the art, and it is intended that all inventive concepts utilizing the inventive concepts set forth herein be protected without departing from the spirit and scope of the present invention as defined and limited by the appended claims.
Claims (10)
1. A large Bi-2212 superconducting coil heat treatment furnace system is characterized by comprising:
the device comprises a pressure-resistant furnace shell, a pressure-resistant furnace cover, a heat-insulating layer, a heating chamber, a temperature-equalizing radiation screen, a pressure-equalizing pipeline, a supporting workbench, a liquid argon tank, an oxygen-argon mixed gas tank, a gas pipeline and a safety device;
a gas pipeline reserved port, a cooling device and a thermocouple reserved port are arranged on the pressure-resistant furnace shell, a hanging ring is arranged above the pressure-resistant furnace cover, and a plurality of groups of reinforcing ribs are arranged below the pressure-resistant furnace cover and connected with the upper heat-insulating layer;
the heat insulation layer is of a sandwich structure and consists of a stainless steel outer screen, a molybdenum inner screen and heat insulation fibers sandwiched between the stainless steel outer screen and the molybdenum inner screen, the heat insulation layer is positioned in the pressure-resistant furnace shell, and the thickness of the heat insulation layer is between 100 and 250 mm;
the heating chamber comprises a heating belt fixed on an inner screen of the heat insulation layer, and the uniform-temperature radiation screen is positioned in the heating chamber and made of high-temperature alloy steel; the uniform temperature radiation screen is positioned above the supporting workbench, an inlet and an outlet of a gas pipeline are reserved on the uniform temperature radiation screen, the Bi-2212 superconducting coil is positioned in the uniform temperature radiation screen, the uniform pressure pipeline is positioned in the heat insulation layer, the heating chamber is communicated with a pressure-resistant furnace shell outside the heat insulation layer, the air pressure inside and outside the heat insulation layer is kept consistent, the supporting workbench is fixed at the bottom of the pressure-resistant furnace shell, penetrates through the heat insulation layer and is a heating workbench for placing the superconducting coil, the oxygen-argon mixed gas tank is used for providing the pressure of 3-5Mpa, and a first stop valve, a first pressure reducer and a first flowmeter are sequentially arranged behind the oxygen-argon mixed gas tank and are in threaded connection with the gas pipeline; the liquid argon tank provides 3-6Mpa of pressure, is equipped with second stop valve, second pressure reducer, second flowmeter, third stop valve behind it in proper order, carries out threaded connection with the gas line, the gas line all have cooling device with withstand voltage stove outer covering continuous part, the gas line divide into samming radiation screen air inlet pipeline, samming radiation screen gas outlet pipeline, withstand voltage stove outer covering air inlet pipeline and withstand voltage stove outer covering gas outlet pipeline, the gas line is connected with safety device, safety device includes first relief valve, second relief valve, rupture disc, first manometer, second manometer and controlling means.
2. The large Bi-2212 superconducting coil heat treatment furnace system according to claim 1, characterized in that:
the pressure-resistant furnace shell is a cylindrical stainless steel tank body, the thickness of the tank body is 5-30mm, the diameter of the disc base is 4-8m, the height of the disc base is 4-9m, and the pressure-resistant furnace shell and the reserved pipeline are sealed in a welding mode.
3. The large Bi-2212 superconducting coil heat treatment furnace system according to claim 1, characterized in that: the pressure-resistant furnace cover is designed in an arch shape, is made of stainless steel materials and has the thickness of 10-30mm, is positioned above the pressure-resistant furnace shell and is connected in a sealing mode in a welding mode.
4. The large Bi-2212 superconducting coil heat treatment furnace system according to claim 1, characterized in that: the total power of the heating chamber is 100-300KW, the heating belt is made of molybdenum materials, the distance between the heating belt and the inner screen of the heat insulation layer is 50-150mm, and each heating area is provided with a standby heating belt.
5. The large Bi-2212 superconducting coil heat treatment furnace system according to claim 1, characterized in that: the temperature-equalizing radiation screen is designed according to the size of the Bi-2212 superconducting coil, the distance between the temperature-equalizing radiation screen and the heating belt is 50-200mm, and the temperature-equalizing radiation screen can bear the pressure of 1 MPa.
6. The large Bi-2212 superconducting coil heat treatment furnace system according to claim 1, characterized in that: the diameter of the hole of the pressure equalizing pipeline is 100-1500mm, the wall thickness is 5-20mm, and the gas inlet and outlet pipelines are respectively positioned in the pressure equalizing pipeline.
7. The large Bi-2212 superconducting coil heat treatment furnace system according to claim 1, characterized in that: the diameter of the hole of the gas pipeline is 20-100mm, the wall thickness is 2-10mm, the gas outlet pipeline of the uniform temperature radiation screen is provided with a third pressure reducer and a first oxygen content analyzer, and the gas outlet pipeline of the pressure-resistant furnace shell is provided with a fourth pressure reducer and a second oxygen content analyzer.
8. The large Bi-2212 superconducting coil heat treatment furnace system according to claim 1, characterized in that: the uniform temperature radiation screen gas outlet pipeline is connected with the pressure-proof furnace shell gas outlet pipeline, the uniform temperature radiation screen gas outlet pipeline is provided with a first safety valve, the pressure-proof furnace shell gas outlet pipeline is provided with a second safety valve, and the pipeline provided with the rupture disk is bridged between the two gas outlet pipelines.
9. The large Bi-2212 superconducting coil heat treatment furnace system according to claim 1, characterized in that: the rated working pressure of the safety valve is 5.5MPa, and the rated working pressure difference of the rupture disk is 1 MPa.
10. A pressure control method of a large Bi-2212 superconducting coil heat treatment furnace system is characterized in that: the method specifically comprises the following steps:
the method comprises the following steps that firstly, gas in the pressure-resistant furnace shell is replaced, a second stop valve of an argon gas inlet pipeline is opened, a second pressure reducer is opened, air in the pressure-resistant furnace shell is emptied, the pressure in the pressure-resistant furnace shell is monitored, and a fourth pressure reducer of an air outlet pipeline is adjusted to maintain the pressure in the pressure-resistant furnace shell within 1 Mpa;
step two, gas replacement in the uniform temperature radiation screen, namely opening a first stop valve of an oxygen-argon mixed gas inlet pipeline, opening a first pressure reducer, emptying air in the uniform temperature radiation screen, monitoring the pressure in the uniform temperature radiation screen, adjusting a third pressure reducer of an outlet pipeline, synchronously performing gas replacement in the pressure-resistant furnace shell and gas replacement in the uniform temperature radiation screen, and respectively adjusting the inlet flow of the oxygen-argon mixed gas pipeline and the inlet flow of the argon pipeline so as to keep the pressure in the uniform temperature radiation screen and the pressure in the pressure-resistant furnace shell synchronous;
monitoring the oxygen content of gas in the pressure-resistant furnace shell by using a second oxygen analyzer, monitoring the oxygen content of gas in the temperature-uniform radiation-resistant screen by using a first oxygen analyzer when the oxygen content of the gas in the pressure-resistant furnace shell is lower than 10ppm, and stopping gas replacement when the oxygen content of the gas in the temperature-uniform radiation screen is consistent with the oxygen content of the oxygen-argon mixed gas;
step four, synchronously pressurizing the furnace, and adjusting a fourth pressure reducer of the pressure-proof furnace shell exhaust pipeline and a third pressure reducer of the temperature-equalizing radiation screen exhaust pipeline to ensure that the pressure in the temperature-equalizing radiation screen and the pressure in the pressure-proof furnace shell are synchronously increased, and finishing pressurization when the two pressures reach 5Mpa simultaneously;
and step five, performing micro-feeding and micro-discharging of gas, adjusting the gas inlet flow of the uniform temperature radiation screen and the pressure-proof furnace shell gas inlet pipeline, performing micro-feeding and micro-discharging of the gas in the uniform temperature radiation screen and the pressure-proof furnace shell, keeping the pressure synchronous, and then heating.
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